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Archived

Avalanche Forecast

Jan 4th, 2012–Jan 5th, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Northwest Inland.

Confidence

Fair - Due to limited field observations

Weather Forecast

A short-lived ridge of high pressure develops over the area on Thursday, bringing mostly dry weather. Freezing levels will be at valley bottom. Winds moderate from the west. On Friday, a weak frontal system will likely bring only flurries or light precipitation with moderate SW winds. On Saturday, a stronger frontal system will give moderate to heavy precipitation, with freezing levels rising to 1500 m and strong southwesterly winds.

Avalanche Summary

High winds and poor visibility have limited observations for the last few days; however, no activity has been reported to us from this region recently. I suspect you could easily trigger a pocket of wind slab on exposed lee terrain and I'd still be nervous of triggering the mid-December surface hoar layer down around 70 cm in sheltered locations.

Snowpack Summary

New snow and strong winds have set up fresh wind slabs at higher elevations, mainly on north through east aspects in exposed lee terrain--these are likely triggerable by riders on sleds or on skis. Lower down, expect a significant rain crust to exist up to approximately 1500 m. There is now approximately 80 to 120cms of storm snow sitting above a surface hoar/crust/facet layer that was buried mid-December. The increasing depth of this weak layer makes it difficult to trigger; however, I wouldn't ignore this layer yet, as it could still be triggered by large loads such as rapid loading by new snow or rain or cornice falls. It could also be triggered by riders in shallow snowpack areas or where rocks poke up near the surface. The mid- and lower snowpack layers are well consolidated and generally strong.

Avalanche Problems

Wind Slabs

Strong southwesterly winds continue to set up touchy wind slabs on mainly north through east aspects.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 6

Storm Slabs

New snow with rising temperatures will set up storm slabs on steep, open slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 5

Persistent Slabs

Persistent slabs are getting harder to trigger but still exist in many locations. The probability of triggering has decreased, but the consequences of a release remain high.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 5